80k om milage

make sure that the squeak is not from dry rings in the bore
put oil down the cylinder and rotate the crank
if it goes it could be just dry and need no further checks but if it is in a bearing then it is serious and needs replacing
turning a crank should produce a dry scraping noise as the pistons move up and down the bores but certainly not other noise

No-have to remove the front cover

Watch the Video on you tube

Has the oil seldom been changed on
that motor since it was new?

Lots to read on problems with that motor

Lack of oil changes
Sludge & Coolant Leaks
Water Pump & Chain issues

Seems most chrysler engines have problems
especially 4 cylinders

Instructions

1. Remove Your Timing Chain
   • 1 Check your owner's manual for the recommended mileage for replacing your timing chain. Replacement for a Nissan Altima is 60,000 miles.
     
   • 2 Locate the timing chain. Replace it if the automatic chain adjuster (also known as the tensioner) is damaged or worn.
     
   • 3 Drain the cooling system and disengage the negative battery cable. Undo the spark plug wires and set the No. 1 piston at "Top Dead Center" (TDC) of the compression stroke.
     
   • 4 Disconnect the engine undercover, vacuum and fuel hoses, harness and connectors, drive belts, power steering reservoir, alternator and bracket, upper radiator hose, air duct, front exhaust tube, intake manifold collector supports, collector and exhaust manifold and the distributor.
     
   • 5 Prop up the oil pan and take out the front engine mounting, the valve cover, camshaft sprockets, cam bearing caps, camshafts, cylinder head bolts (reverse the installation order), cam sprocket cover, upper chain tensioner, chain guides and chain, idler sprocket bolt, cylinder head, intake manifold and cylinder head gasket and the steel oil pan.
     
   • 6 Place a steel cutter between the steel and aluminum oil pans. Slip the cutter around the oil pan's edge. Disengage the steel oil pan, baffle plate, oil strainer and the front tube.
     
   • 7 Secure the car on jack stands and place a seal cutter in between the oil pan and cylinder block. Slip the cutter around the oil pan's edge.
     
   Install Your Timing Chain
   • 8 Reconnect the crankshaft sprocket, oil pump drive spacer, idler sprocket and lower timing chain. Position the lower timing chain on the sprockets and line up the mating marks.
     
   • 9 Rub on an unbroken bead of liquid gasket and put in a new front cover and oil seal. Secure the bolt at 105 to 112 foot pounds (142 to 152 Nm).
     
   • 10 Eliminate any old material from the pan and cylinder block mounting surfaces. Rub on a 3.5 to 4.5mm bead of liquid gasket over the oil pan and cylinder block.
     
   • 11 Attach the upper timing chain to the idler sprockets and secure the cylinder head bolts.
     
   • 12 Refill the cooling system and add clean oil in the engine.
     
   • 13 Hook up the negative battery cable and any other disconnected parts or items. Start the engine and look for leaks.
     

Tips & Warnings

• Procedures for replacing timing chains in Nissan Altimas vary slightly depending on engine size.
  
• Make sure the new timing chain matches the chain you are removing.
  

Check your owner's manual for the recommended mileage for replacing your timing chain. Replacement for a Nissan Maxima is 60,000 miles.2 Locate the timing chain. Replace it if the automatic chain adjuster (also known as the tensioner) is damaged or worn.3 Release the pressure in the fuel system, drain the cooling system and disengage the negative battery cable. 4 Undo the upper radiator hose, engine drive belts, power steering pulley and pump with bracket, air duct, passenger front wheel and engine side and undercovers, front exhaust pipe, cylinder head front mounting bracket and head cover, rocker cover, distributor and distributor cap and spark plugs.5 Take off the intake manifold support and move the No. 1 piston at "Top Dead Center" (TDC) of the compression stroke.6 Disconnect the cylinder head front cover, water pump pulley, thermostat housing, upper and lower tensioner and slack side timing chain guide, idler sprocket bolt, camshaft sprocket bolts, sprockets, mounting caps and camshafts. 7 Disengage the cylinder head with the manifolds, idler sprocket shaft, upper timing chain, center crossmember, oil pan and strainer assembly, crankshaft pulley, engine front mount and bracket and the front timing cover. Remove the oil seal and unfasten the timing chain cover, idler and crankshaft sprockets and the oil pump drive spacer. 8 Unfasten the timing chain guide. install Your Timing Chain 1 Grease the oil seal lip with engine oil and place it in the front cover. Verify that the No. 1 piston is at "Top Dead Center" (TDC) of the compression stroke. 2 Reconnect the crankshaft sprocket (marks should point toward the engine's front), oil pump drive spacer and timing chain guide and the lower timing chain. Line up all mating marks.3 Hook up the crankshaft sprocket and pulley, lower timing chain, front cover assembly, engine mount and front mounting bracket, oil strainer and pan assembly and center crossmember.4 Reattach the upper timing chain, idler sprocket (to the back side), cylinder head assembly, idler sprocket bolt and exhaust and intake camshafts. Place the intake camshaft knock pin at 9 o'clock and the exhaust pin at noon. Connect the camshaft bearing caps and distributor brackets and secure all mounting bolts.5 Eliminate any old material from the pan and cylinder block mounting surfaces. Rub on a 3.5 to 4.5mm bead of liquid gasket over the oil pan and cylinder block.6 Attach the upper timing chain to the idler sprockets and secure the cylinder head bolts.7 Refill the cooling system. Hook up the negative battery cable and any other disconnected items. Start the engine and look for leaks.

Timing belt change is 80k with water pump

Hi the trick with this engine is early oil and oil filter changes to minimise chain wear as they
tend to get very noisey around the 80k mark and often fail before 90k destroying the valves and
pulling off the bottom chain sprocket that is only pressed on to the crankshaft so thats no good either my advise is to run it to 70k if you have to and get something else before it self destructs

Installation
Install crankshaft sprocket on crankshaft.
Make sure mating marks on crankshaft sprocket face front of engine.

Position crankshaft so that No. 1 piston is at TDC and crankshaft key is at 12 o'clock.

Install slack side timing chain guide and timing chain tension guide.

Install timing chain on crankshaft sprocket.
Set timing chain by aligning its mating mark with that on the crankshaft sprocket.
Make sure sprocket's mating mark faces engine front.

Install camshaft sprockets.
Set timing chain by aligning mating marks with those of camshaft sprockets.

Install camshaft sprocket bolts to correct torque.
Apply new engine oil to bolt threads and seat surface.

Install chain tensioner.
Before installing chain tensioner, insert a suitable pin into pin hole of chain tensioner.
After installing chain tensioner, remove the pin.
Install timing chain guide.

Install O-rings to cylinder block.

Before installing front cover, remove all traces of RTV silicone sealant from mating surface using a scraper.
Also remove traces of RTV silicone sealant from mating surface of cylinder block.

Apply a continuous bead of Genuine RTV Silicone Sealant or equivalent to mating surface of front cover. Refer to RECOMMENDED CHEMICAL PRODUCTS AND SEALANTS .
Check alignment of mating marks on chain and crankshaft sprocket.
Align oil drive spacer with oil pump.
Place timing chain to the side of chain guide. This prevents the chain from making contact with water seal area of front cover.

Install front cover.

Make sure two O-rings are present.

Be careful not to damage oil seal when installing front cover.
Install cylinder head bolts at engine front side as shown in Fig. 55.
Tightening procedure:
Tighten bolts (1 - 4): 6.3-8.3 N.m (0.64-0.85 kg.m, 55.8-73.5 in.lb).

Install oil pump drive spacer.
Install water pump and water pump pulley. Refer to REMOVAL AND INSTALLATION .
Install idler pulley and bracket.

Install RH engine mounting bracket

Install RH engine mounting.
Install oil pan. Refer to INSTALLATION.
Install crankshaft pulley.
Remove ring gear stopper.
Install starter motor.
Install cylinder head front cover.
Apply RTV silicone sealant to cylinder head front cover.
Use Genuine RTV Silicone Sealant or equivalent. Refer to RECOMMENDED CHEMICAL PRODUCTS AND SEALANTS .

Install Camshaft Position Sensor (PHASE).

Before installing rocker cover, apply a bead of Genuine RTV Silicone Sealant or equivalent, to mating surface of cylinder head as shown in .

Install rocker cover gasket into rocker cover.
Install rocker cover and tighten in numerical order as shown in
Install spark plugs.
Install ignition coils.
Install front exhaust tube.
Install front/right-side splash undercover.
Install front RH wheel.
Install drive belts.
Adjusting drive belt deflection..

I recently purchased a 2004 Ascender with the 4.2l in-line six cylinder motor, and under the 60 day warranty, the fan clutch and water pump had to be replaced. The mechanic told me that the fan clutch wears out causing an out-of-balance condition which puts extra strain on the water pump, which was leaking. Another issue may be that the timing chain needs to be looked at, because the tension wheel/gear for the chain wears out, making the timing chain sloppy. Then the chain flops around inside the housing, making a similar noise to the one you describe. Have your mechanic/technician check it out.

REMOVAL & INSTALLATION NOTE: The manufacturer recommends that the entire powertrain be removed from the vehicle before removing the cylinder heads.

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Drain the cooling system.
3. Properly relieve the fuel system pressure.
4. Remove or disconnect the following:
   • Negative battery cable
   • Powertrain assembly
   • Intake manifold
   • Cam covers
   • Harmonic balancer
   • Timing chain front cover
   • Oil pump
   WARNING
   Align all timing marks before performing the next step.
   • Chain tensioner from the timing chain
   • Cam sprockets
   NOTE: The timing chain remains in the chain case.
   • Timing chain guides, access for the retaining screws is through the plugs at the front of the cylinder head
   • Water crossover
   • Exhaust manifold
   • Cylinder head bolts by reversing the torque sequence
   • Cylinder head and discard the gasket
   WARNING
   With the camshafts remaining in the cylinder head some valves will be open at all times. Do not rest the cylinder head on a flat service with the cylinder face down, or valve damage will result. NOTE: Clean all gasket mating surfaces. Clean the head bolt holes in the crankcase. WARNING
   Be careful when cleaning aluminum gasket surfaces to prevent damage to the sealing surfaces.
   
5. Check the cylinder head for warpage; it must be less than 0.002 in. (0.05mm). If the cylinder head was resurfaced, the dimension between the combustion chamber gauge pad and the deck surface must be at least 10.5mm. To install: NOTE: Refer to Section 1 of this manual for the cylinder head torque sequence illustration. The illustration is located after the Torque Specification Chart.
   
6. Install or connect the following:
   • New cylinder head gasket
   • Cylinder head, lubricate the bolts with engine oil
7. Torque the M11 bolts, in sequence, as follows:
   1. Step 1: 22 ft. lbs. (30 Nm).
   2. Step 2: Turn an additional 60 degrees.
   3. Step 3: Turn an additional 60 degrees (total 180 degrees).
8. Torque the M6 bolts to 106 inch lbs. (12 Nm).
9. Set the camshaft timing
10. Camshaft guide bolt access hole plugs in the cylinder heads. The plugs should be seated and snug
11. Install or connect the following:
    • Intake cam covers
    • Oil pump
    • Timing chain front cover
    • Harmonic balancer
    • Cam sprockets
    • Chain tensioner to the timing chain
    • Timing chain guides
    • Intake manifold
    • Water crossover
    • Exhaust manifold. Torque the nuts to 22 ft. lbs. (30 Nm) or the bolts to 18 ft. lbs. (25 Nm).
    • Powertrain assembly
    • Negative battery cable Fig. 1: Minimum head resurface dimension
      
    
    
12. Fill the cooling system.
13. Evacuate and charge the air conditioning system.
14. Run the engine and check for leaks.

CHECK FOR LEAKING WATER PUMP WEEP HOLE OR GASKET.ALSO CHECK WATER PUMP HOSE FOR LEAKS.IF ALL LOOKS GOOD.YOU COULD HAVE PINHOLE LEAKS IN RADIATOR CORE LEAKING ON FRONT OF ENGINE OR INTAKE MANIFOLD GASKET LEAKING COOLANT.